From the degree of illumination the globe there are several such belts - one tropical, temperate and polar, one each in the northern and southern hemispheres.

There are only five light belts:

• Tropical;
• Moderate - North, South;
• Polar - North, South.

Tropical Illumination Belt

So, the boundaries of the tropical illumination belt are the southern and northern tropics - parallels with the corresponding geographical coordinates - 23.44 ° south latitude and the same 23.44 ° north. Above these parallels and within the tropical illumination belt, sunlight still forms a right angle of incidence with the Earth's surface, that is, the Sun will be at its zenith (objects and objects on the surface do not cast a shadow at this moment). The relief of the Earth between these tropics receives the maximum amount of solar heat and light. This occurs at the time of the winter (for the southern tropics) and summer (for the northern tropics) solstice.

Moderate light belts

Further beyond the boundaries of the tropical illumination belt, towards the poles, there are zones of moderate illumination zones. A distinctive feature is the average illumination, which, moreover, strongly depends on the annual position of the Earth relative to the Sun, that is, in winter time year there will be one level of incoming light from the sun, and in summer another. Accordingly, the degree of heat received by the Earth's surface will not be the same. In areas of temperate zones of illumination, the Sun never reaches the zenith position throughout the year. The boundaries of the temperate zone of illumination of the northern hemisphere will be the latitude of the Northern Tropic at 23.44 ° and the latitude of the Arctic Circle at 66.56 °, for the Southern Hemisphere, respectively, the Southern Tropic and the Arctic Circle with the corresponding coordinates in the parallels.

Polar light belts

The polar belts of illumination (north and south) lie outside the polar circles (at 66.56 °) in both hemispheres. Here, the illumination of the Earth's surface is minimal. The boundary of the polar belt of illumination is defined by the parallel, above which the Sun reaches its highest point above the horizon in December at the time of the solstice - this is 66.56 ° north latitude. Similarly, for a southern latitude of 66.56 °, where the solar disk is visible at its highest point only in June at the time of the solstice.

Rice. 1. Light belts of the Earth

Illumination belt boundary

During the polar day, within the poles, the sun is closer to the horizon and does not rise high. Solar streams of light, due to the small angle of incidence, slightly heat the surface, mostly reflected from the snow-covered plains and mountain ice rocks. And on a polar night, the sun stays behind the horizon. In these latitudes, the temperature drops are 35 ° C - 65 ° C. The formation of such a climate depends on the degree of heating of the earth's surface, that is, on how effectively this part of the Earth is illuminated by the Sun.

The division of zones according to the amount of incoming sunlight among themselves determines the presence of the boundaries of the illumination belts.

So what is the boundary of the light belts? These are conventionally accepted parallels that separate the areas of illumination of the planet - the Northern Tropic and the Southern, the Arctic Circle and the Southern.

Light zones - climate formation

The sun is a heat source that heats earth surface and ambient air. Sunlight, which carries heat with it, falls on the planet's surface at different latitudes at its own angle, which leads to an unequal degree of heat absorption by the surface.

For example, in equatorial latitudes, the angle of incidence of sunlight is 90 ° - the earth's surface receives maximum heat, and in northern latitudes, the angle of incidence is 30 ° - these areas of the planet are heated less.

Thanks to varying degrees illumination, certain zones of illumination of the Earth and their boundaries are formed. This determines the difference in climate in the northern, temperate and equatorial latitudes of the globe.

Let's clarify right away - heat zones and zones of illumination of the Earth have different boundaries and are not identical. Heat zones primarily depend on mountain building, availability coastal areas- contact of seas and oceans with continents, from different directions of the flow of water in the oceans, from the distribution of air currents and the amount of precipitation.

Why is the surface temperature and air masses at the equator does not change so much compared to northern latitudes? Because the angle of incidence of sunlight throughout the year changes by a small amount.

As a result of the above, the light belts border each other. The boundaries of the light belts are parallels at 23.44 ° and 66.56 ° north and south latitudes. Otherwise, these border lines are called the North and South Tropics, the North Polar and South Polar Circles - these are four of the five main parallels marked on.

With the help of this video tutorial, you can independently study the topic "The distribution of sunlight and heat". First, discuss what determines the change of the seasons, study the diagram of the annual rotation of the Earth around the Sun, paying special attention to the four most remarkable dates in terms of the sun's illumination. Then you will find out what determines the distribution of sunlight and heat on the planet and why it is uneven.

Rice. 2. Illumination of the Earth by the Sun ()

In winter, the southern hemisphere of the Earth is better illuminated, in summer - the northern one.

Rice. 3. Scheme of the annual rotation of the Earth around the Sun

Solstice (summer solstice and winter solstice) - moments when the height of the Sun above the horizon at noon is highest (summer solstice, June 22) or lowest (winter solstice, December 22). In the southern hemisphere, the opposite is true. June 22 in the northern hemisphere is the highest illuminance by the Sun, day longer than night, a polar day is observed beyond the polar circles. In the southern hemisphere, again, the opposite is true (i.e. all this is typical for December 22).

Polar Circles (Arctic Circle and Antarctic Circle) - parallels, respectively, with latitude north and south about 66.5 degrees. North of the Arctic Circle and south of the Antarctic Circle, there is a polar day (in summer) and a polar night (in winter). The region from the Arctic Circle to the Pole in both hemispheres is called the Arctic Circle. Polar day - a period when the Sun at high latitudes does not descend beyond the horizon around the clock.

polar night - the period when the Sun at high latitudes does not rise above the horizon around the clock - a phenomenon opposite to the polar day is observed simultaneously with it at the corresponding latitudes of the other hemisphere.

Rice. 4. Scheme of the illumination of the Earth by the Sun by zones ()

Equinox (vernal equinox and autumnal equinox) - moments when the sun's rays touch both poles and fall vertically at the equator. The vernal equinox occurs on March 21st, and the autumnal equinox occurs on September 23rd. These days both hemispheres are lit the same, day is equal to night,

The main reason for the change in air temperature is a change in the angle of incidence of the sun's rays: the more vertically they fall on the earth's surface, the better they warm it up.

Rice. 5. The angles of incidence of the sun's rays (at the position of the Sun 2, the rays warm up the earth's surface better than at position 1) ()

On June 22, the sun's rays fall most steeply on the northern hemisphere of the Earth, thereby most warming it up.

Tropics - The Northern Tropic and the Southern Tropic are parallels, respectively, with the north and south latitude of about 23.5 degrees. On one of the solstice days, the Sun at noon is above them at its zenith.

The tropics and polar circles divide the Earth into light belts. Illumination belts - parts of the Earth's surface bounded by the tropics and polar circles and differing in lighting conditions. The warmest zone of illumination is tropical, the coldest is the polar one.

Rice. 6. Light belts of the Earth ()

The sun is the main luminary, on the position of which the weather on our planet depends. The moon and other cosmic bodies have an indirect effect.

Salekhard is located on the line of the Arctic Circle. An obelisk to the Arctic Circle has been erected in this city.

Rice. 7. Obelisk to the Arctic Circle ()

Cities where you can watch the polar night: Murmansk, Norilsk, Monchegorsk, Vorkuta, Severomorsk, etc.

Homework

Clause 44.

1. Name the days of the solstice and the days of the equinox.

Bibliography

The main

1. Initial course geography: textbook. for 6 cl. general education. institutions / T.P. Gerasimova, N.P. Neklyukova. - 10th ed., Stereotype. - M .: Bustard, 2010 .-- 176 p.

2. Geography. Class 6: atlas. - 3rd ed., Stereotype. - M .: Bustard; DIK, 2011 .-- 32 p.

3. Geography. Class 6: atlas. - 4th ed., Stereotype. - M .: Bustard, DIK, 2013 .-- 32 p.

4. Geography. 6 cl .: cont. maps: M .: DIK, Bustard, 2012 .-- 16 p.

Encyclopedias, dictionaries, reference books and statistical collections

1. Geography. Modern Illustrated Encyclopedia / A.P. Gorkin. - M .: Rosmen-Press, 2006 .-- 624 p.

Literature for preparing for the State Examination and the Unified State Exam

1. Geography: Initial course: Tests. Textbook. manual for students of 6 cl. - M .: Humanit. ed. center VLADOS, 2011 .-- 144 p.

2. Tests. Geography. 6-10 cells: Study guide/ A.A. Letyagin. - M .: OOO "Agency" KRPA "Olymp": "Astrel", "AST", 2001. - 284 p.

1.Federal Institute of Pedagogical Measurements ().

2. Russian geographic society ().

3.Geografia.ru ().

Question 1. What is the feature of the distribution of sunlight over the surface of the Earth?

The fact that the axis of rotation of the Earth is slightly inclined to the plane of the Earth's orbit. The angle formed by the earth's axis and the plane of the orbit is 66.5.

Question 2. What areas of the earth receive the most sunlight? Least amount?

The equatorial zone and the tropics receive the greatest amount of light. The North and South poles receive the least amount of light.

Question 3. What special days associated with different levels of illumination of the Earth are on the calendar?

The vernal equinox is March 21, the autumn equinox is September 23. The summer solstice is June 22, the winter solstice is December 22.

Question 4. How would the degree value change geographic latitude tropics and polar circles with a change in the angle of inclination of the earth's axis?

They would change the value of latitude along with the earth's axis.

Question 5. What is the tropic?

The tropic is a parallel on which on the days of the solstices the sun is at its zenith at noon, that is, exactly overhead.

Question 6. What parallels on the map are called the polar circles?

The polar circles are the parallels behind which the polar nights and days are observed.

Question 7. What is the value of the latitude of points located in the tropics, polar circles?

The tropics have a constant value of the geographical latitude - 23.5 ". The Arctic circles have a constant value of the geographical latitude - 66.5 °.

Question 8. What is an illumination belt?

Illumination belts are called areas of the planet that are illuminated in different ways by the sun and receive different amounts of heat.

Question 9. What are the belts of illumination?

The part of the globe that lies between the two tropics is called the tropical illumination belt. The North and South polar belts are the coldest and harshest regions on our planet. There are two temperate zones between the tropical and polar zones of illumination.

Question 10. What are the boundaries of the light belts?

The tropics and polar circles are the boundaries of the zones of illumination.

Question 11. What is the minimum length of the polar night?

The shortest polar night (almost two days) is observed at a latitude of ≈ 67 ° 3 ′ n. NS.

Question 12. At what angle of inclination of the earth's axis in your settlement could you observe polar night and day?

To observe polar day and night, it is necessary that the angle of inclination of the earth's axis is 56 °.

Question 13. Make a description natural conditions, typical for different zones of illumination.

The tropics are characterized by a humid tropical climate, the closer to the equator, the more arid climate. The temperate zones are characterized by a warm climate, with warm (sometimes hot) summers and cool (sometimes cold) winters. The polar circles are characterized by a cold and very cold climate.

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Slide captions:

What is climate? What are the climate-forming factors? Using the textbook picture on page 139, determine how the climate changes as you move from west to east? What is the climate in Kaliningrad, in Petropavlovsk-Kamchatsk?

What movements of the Earth do you know? Daily movement.

Annual movement.

The earth's axis has a constant tilt of 66.5

e June 22 is the day of the summer solstice. December 22 is the day of the winter solstice. March 21 is the day of the vernal equinox. September 23 - the day of the autumnal equinox

The tropics are the lines above which the sun is at its zenith. The Arctic Circle is a parallel where the polar night is observed on the solstice days.

Heat zones.

The longest day in the Northern Hemisphere June 22 Day of the Summer Solstice The shortest day in the Northern Hemisphere Day is equal to night Fill in the table Anchor: So how is sunlight and heat distributed on Earth? (evenly or unevenly?) REFLEXION.

Position of the Earth (dates) What time of year in your area Where is the sun at its zenith Where is the polar day 22 June 23 September 22 December 21 March Task 2. Underline the dates for which the illumination of the Earth is shown. (self-test) Task 3. Fill in the table

1 2 3 Which light belts are indicated by numbers?

Homework: 46. outline map in the atlas, mark the conditional lines: equator, tropics, polar circles. Shade the light belts.

Knowledge test - option 1. 1. The boundaries of the tropical zone of illumination are on _____________________ 2. What time of the year will be in the northern hemisphere if summer is in the southern hemisphere ____________________________________________ 3. What is the name of the parallel above which once a year the midday Sun is at its zenith, ie. the sun's rays fall vertically ___________________ 4. What is the name of the parallel 66.5 * N lat. and 66.5 * S _______________ 5. What day of the year is the Summer Solstice ____________________ 6. What day of the year is the Spring Equinox ________________ 7. In what heat zones is Africa located? 8. At what point on June 22 the Sun is higher: A (25 * N), b (60 * N) B (25 * S) Option 2 1. The border between the polar and moderate illumination belt runs along ________________________________________________ 2. What time of year will be in the northern hemisphere if winter is in the southern hemisphere _____________ 3. What is the name of the parallel, beyond which there is a polar day and a polar night ____________________ 4. What is the name of the parallel 23.5 * N. and 23.5 * S __________________ 5. What day of the year is the Winter Solstice ___________________ 6. What day of the year does the Autumn Equinox occur _____________ 7. In what heat zones is North America located? 8. At what point on December 22 is the Sun higher: A (25 * N), b (60 * N) B (25 * S) ____

As a result of the sphericity of the planet, when the sun's rays move to the poles from the equator, the angle of incidence of the rays decreases. At the Poles of the planet, the height of the Sun will be small during the day, and near the equator it will reach a huge state. Because of this, an isolated unit of area receives less and less light and solar heat.

The uneven distribution of light and solar heat led to the fact that the Earth's surface was divided into belts of illumination. There are five different light belts, and their boundaries are the polar circles and the tropics. List of belts:

• moderate illumination belt (two);
• illumination belt cold (two);
• the light belt is hot.

The listed belts were formed due to the inclination of the Earth's axis of rotation to the orbital plane, as well as due to the movement of the Earth around the Sun.

The illumination belt is part of the Earth's surface. This part is limited to the polar circles and the tropics, has special lighting conditions.

Illumination is the flux of sunlight falling on a unit of a specific surface.

The difference between the belts from each other lies in the following factors:

• thermal conditions and different air temperatures;
• length of the day;
• different natural conditions;
• the height of the midday Sun above the horizon.

December 22 and June 22, once a year, in the Southern and Northern Tropics, you can trace the sheer fall of the sun's rays. On the same dates, once a year, there is a polar day and a polar night, characteristic of the polar South and Arctic circles.

Moderate light belts

There are two temperate zones. One of them is located in the Northern Hemisphere, the other in the Southern Hemisphere. Both belts are located between the tropics and the polar circles, and adjoin the hot belt. In the presented belts of illumination, the sun's rays descend to the Earth at a certain inclination. The closer to the north, the more the slope will be more and more. This means that the surface of the planet will heat up less and the temperature will not be as hot. Characteristic feature belts of the temperate plan is that in them the sun is never at its zenith. In such belts, the seasons are clearly expressed. This means that during the approach to the Arctic Circle, the winter becomes very cold and long, and during the approach to the tropics, a warm and long summer begins. Moderate light belts are limited by the isotherm from the side of the poles. The isotherm is the boundary of the forest distribution. More than half of the earth's surface is in moderate light belts. During the summer periods in northern cities you can watch the white nights. Moreover, during the summer periods, the length of the day increases markedly, and the length of the night decreases. In winter it is the other way around.

Hot Belt of Illumination

The hot belt of illumination occupies almost 40 percent of the Earth's surface. This belt is located between the southern and northern tropics. The sun is always located high above the horizon in a hot zone. This means that the surface of the Earth will be perfectly warmed up. In hot zones of illumination there is no difference between winter and summer temperatures, and there are no thermal seasons at all. The air temperature is approximately 25+ degrees Celsius. Both daylight hours and nighttime are approximately equal. Their duration is about twelve hours. In such zones of illumination there is no twilight, and the sun is at its zenith only a few times a year: in the South and North tropics. The boundaries of the hot zone of illumination coincide with the boundaries of the distribution of corals in the ocean and palms on land. The belt is called hot because it receives the greatest amount of heat per year.

Cold light belts

There are two cold zones in the world. One of them is located in Southern hemisphere, and the second - in the North. Cold light belts occupy no more than 8 percent of the planet's territory. These belts are located inside the polar circles. These are the most interesting belts to consider, as they have extremely strange conditions for the distribution of light and solar heat. V winter periods the sun in the presented belts is not shown at all over the horizon. Thanks to this, you can observe such a phenomenon as the polar night. During periods of summer, the Sun does not have time to hide behind the horizon. Thanks to this, you can observe the polar day. Closer to the poles, the duration of polar nights and polar days increases, and begins to reach six months. In such zones, summers are short and cool, and nights are harsh and cold. The surface of the Earth heats up weakly, practically does not provide heat, since the angle of the sun's rays is extremely small. When the polar night is outside, there is practically no heat flow.

Polar day is a unique period of time during which the Sun is at high latitudes and does not cross the horizon, does not descend beyond it.

At the North Pole, closer to the pole itself, the duration of such a day can reach 169 days. At the South Pole, this figure is slightly lower. This is due to the uneven speed of the Earth. On the polar circle, that is, on a parallel value, a day can last about forty days.

The polar night is a unique period of time during which the Sun is at high latitudes and does not cross the horizon, does not rise above it.

The phenomenon of the polar night is diametrically opposite to the phenomenon of the polar day. It can be observed in both the Southern and Northern Hemispheres. The polar night is almost always shorter than the polar day.

Of all the belts of illumination that exist on the planet, the most comfortable belts with living conditions are considered to be temperate belts, stretching to hot ones. Cold belts count as places eternal ice, and hot ones are too uncomfortable for life.

Illumination of the Earth's surface and impact on health

Everyone knows that daylight plays a key role in people's lives. Daylight not only provides visual perception, but also affects the central processes of life. It regulates resistance to adverse factors the environment and affects the metabolism. The alternation of day and night is a natural process. And the perception of natural light by a person is an element of his internal clock.

And, on top of that, lighting affects people's performance and mood ...